With this trick from CCAN (http://ccodearchive.net/info/array_size.html)
we ensure at build-time user is indeed passing an array and not a
pointer.
The code in CCAN uses several other macros like BUILD_ASSERT,
BUILD_ASSERT_OR_ZERO. Since this is a public header, i think it's
preferred not to export these other macros, unless there's interest in
them.
---
.gitignore | 1 +
Makefile.am | 4 +++-
ell/util.h | 4 +++-
unit/test-util.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 66 insertions(+), 2 deletions(-)
create mode 100644 unit/test-util.c
diff --git a/.gitignore b/.gitignore
index 81c83c7..01a9406 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,6 +38,7 @@ unit/test-netlink
unit/test-dbus
unit/test-dbus-message
unit/test-array
+unit/test-util
doc/*.bak
doc/*.stamp
diff --git a/Makefile.am b/Makefile.am
index e822cd8..37b1781 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -61,7 +61,7 @@ noinst_PROGRAMS = unit/test-unit unit/test-queue \
unit/test-plugin unit/test-checksum \
unit/test-settings unit/test-netlink \
unit/test-dbus unit/test-dbus-message \
- unit/test-array
+ unit/test-array unit/test-util
unit_test_unit_LDADD = ell/libell-private.la
@@ -91,6 +91,8 @@ unit_test_dbus_message_LDADD = ell/libell-private.la
unit_test_array_LDADD = ell/libell-private.la
+unit_test_util_LDADD = ell/libell-private.la
+
noinst_LTLIBRARIES += unit/example-plugin.la
unit_example_plugin_la_LDFLAGS = -no-undefined -module -avoid-version \
diff --git a/ell/util.h b/ell/util.h
index d7849c1..3c9b14f 100644
--- a/ell/util.h
+++ b/ell/util.h
@@ -52,7 +52,9 @@ do { \
__p->__v = (val); \
} while(0)
-#define L_ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#define L_ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
+ sizeof(char[1 - 2 * !!__builtin_types_compatible_p(typeof(x), \
+ typeof(&(x)[0]))]) - 1)
void *l_malloc(size_t size) __attribute__ ((warn_unused_result, malloc));
void l_free(void *ptr);
diff --git a/unit/test-util.c b/unit/test-util.c
new file mode 100644
index 0000000..ec7fecf
--- /dev/null
+++ b/unit/test-util.c
@@ -0,0 +1,59 @@
+/*
+ *
+ * Embedded Linux library
+ *
+ * Copyright (C) 2011-2012 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <ell/ell.h>
+#include <assert.h>
+
+static void array_size1(const void *data)
+{
+ const char dummy[20];
+
+ assert(L_ARRAY_SIZE(dummy) == 20);
+}
+
+struct a {
+ int n;
+ const char *s;
+};
+
+static void array_size2(const void *data)
+{
+ struct a dummy[] = {
+ { 20, "test 1" },
+ { 30, "test 2" }
+ };
+
+ assert(L_ARRAY_SIZE(dummy) == 2);
+}
+
+int main(int argc, char *argv[])
+{
+ l_test_init(&argc, &argv);
+
+ l_test_add("array-size1", array_size1, NULL);
+ l_test_add("array-size2", array_size2, NULL);
+
+ return l_test_run();
+}
--
1.7.10.2
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